Most digital imaging devices such as digital cameras or digital camcorders include some kind of automatic white balance algorithm. The digital imaging device attempts to determine the type of illuminant present in a scene and selects the “white point” accordingly. The white point is the reference color that represents white and with respect to which all other colors in a particular image are calculated. The decision of what kind of illuminant is present is based solely on the current image.
A problem arises, however, when more than one type of illuminant is present in a scene. For example, a room may be illuminated in part by fluorescent lighting and in part by sunlight shining through a window. If successive similar digital images of such a scene are captured, the white balance may end up being inconsistent from image to image because the digital imaging device may set the white balance based on one type of illuminant in one image and a different illuminant in a successive image. This inconsistency in white balance is especially troublesome in live preview and video applications.
It is thus apparent that there is a need in the art for a method and apparatus for maintaining consistent white balance in successive digital images.